1、Designation:F1645/F1645M07 Designation: F1645/F1645M 12Standard Test Method forWater Migration in Honeycomb Core Materials1This standard is issued under the fixed designation F1645/F1645M; the number immediately following the designation indicates the yearof original adoption or, in the case of revi
2、sion, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of water migration in honeycomb core materials.1.2 The val
3、ues stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text theinch-pound units are shown in brackets. The values stated in each system aremay not be exact equivalents; therefore, each systemmustshall be used independently of the other. Combining valu
4、es from the two systems may result in non-conformance with thestandard.1.2.1 Within the text the inch-pound units are shown in brackets.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to e
5、stablish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C271/C271M Test Method for Density of Sandwich Core MaterialsC274 Terminology of Structural Sandwich ConstructionsD883 Terminology Relatin
6、g to PlasticsD3878 Terminology for Composite MaterialsD5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix CompositeMaterialsE122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lo
7、t orProcessE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE1309 Guide for Identification of Fiber-Reinforced Polymer-Matrix Composite Materials in DatabasesE1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced
8、 Composite Materials in Databases3. Terminology3.1 DefinitionsTerminology D3878 defines terms relating to high-modulus fibers and their composites. Terminology C274defines terms relating to structural sandwich constructions. Terminology D883 defines terms relating to plastics. Terminology E456and Pr
9、actice E177 define terms relating to statistics. In the event of a conflict between terms, Terminology D3878 shall haveprecedence over the other terminologies.3.2 Symbols:CV = coefficient of variation statistic of a sample population for a given property (in percent)Sn-1= standard deviation statisti
10、c of a sample population for a given propertyx1= test result for an individual specimen from the sample population for a given propertyx = mean or average (estimate of mean) of a sample population for a given propertyVc= volume of water necessary to fill one core cellVf= volume of water transfusedWc
11、= mass of specimen after filling the primary cell with waterWf= mass of specimen after water transfusion1This test method is under the jurisdiction of ASTM Committee D30 on Composite Materials and is the direct responsibility of Subcommittee D30.09 on SandwichConstruction.Current edition approved Ma
12、yApril 1, 2007.2012. Published June 2007.May 2012. Originally approved in 1995. Last previous edition approved in 20052007 asF164500(2005).F1645 07. DOI: 10.1520/F1645_F1645M-0712.2For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at serviceastm.or
13、g. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit
14、 may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr H
15、arbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Wi= mass of specimen after conditioning, prior to water introduction4. Summary of Test Method4.1 This test method consists of bonding a honeycomb core material to transparent facings using a water-resistant adhesive,drilling a
16、n access hole through one facing to an individual core cell, filling the cell with water, subjecting the filled cell to a constanthydrostatic pressure by maintaining a specified water column height, then measuring the amount of water transferred into thehoneycomb core specimen (primarily due to diff
17、usion through the cell walls) within a 24-h period. The amount of water transferredis presented as an approximate number of honeycomb core cells filled with water.5. Significance and Use5.1 Water permeability is a fundamental physical property that can be used in conjunction with other properties to
18、 characterizehoneycomb sandwich core materials. Migration testing can be used to characterize and compare the relative permeability ofhoneycomb core materials to water.5.2 This test method provides a standard method of characterizing the rate of water migration within honeycomb sandwich corematerial
19、s for design properties, material specifications, research and development applications, and quality assurance.5.3 Factors that influence water migration rate characteristics of honeycomb sandwich core materials and shall therefore bereported include the following: core material, methods of material
20、 fabrication, core geometry (cell size), core thickness, corethickness uniformity, cell wall thickness, specimen geometry, specimen preparation, specimen conditioning, facing material, facingpermeability, adhesive permeability, adhesive thickness, and methods of mass, volume, and water column height
21、 measurement.6. Interferences6.1 Material and Specimen PreparationPoor material fabrication practices and damage induced by improper specimenmachining are known causes of high data scatter in composites and honeycomb sandwich structures in general. Important aspectsof honeycomb sandwich core specime
22、n preparation that contribute to data scatter include the existence of joints, voids or other corediscontinuities, out-of-plane curvature, and surface roughness.6.2 Core GeometryCore-specific geometric factors that affect honeycomb core material water migration rate include core cellsize, uniformity
23、 of core cell geometry, core cell thickness, core cell thickness uniformity, core thickness, and core thicknessuniformity.6.3 FacingsResults are affected by the permeability of the facing material and the flatness of the facing bonding surfaces.6.4 AdhesiveResults are affected by the permeability of
24、 the adhesive, the adhesive thickness, and the thickness uniformity ofthe adhesive. Results are also affected by the presence of voids, cracks, and other defects which compromise the complete bondingof the cell walls to the facings.6.5 EnvironmentResults are affected by the environmental conditions
25、under which specimens are conditioned, as well as theconditions under which the tests are conducted. Specimens tested in various environments can exhibit differences in watermigration rate.7. Apparatus7.1 Micrometers and CalipersA micrometer having a flat anvil interface, or a caliper of suitable si
26、ze, shall be used. Theaccuracy of the instrument(s) shall be suitable for reading to within 1.0 % of the sample length, width and thickness. For typicalspecimen geometries, an instrument with an accuracy of 625 m 60.001 in. is desirable for thickness measurement, whereasan instrument with an accurac
27、y of 6250 m 60.010 in. is acceptable for length and width measurement.7.2 Balance or Weighing ScaleIf the amount of water transferred into the honeycomb core material specimen is to bemeasured by mass, an analytical balance or weighing scale is required that is capable of measuring the initial mass
28、of thehoneycomb core material specimen accurately to 60.5 %.7.3 SyringeIf the amount of water transferred into the honeycomb core material specimen is to be measured volumetrically,a graduated syringe is required that is capable of measuring accurately to 610 mm360.0005 in.3.7.4 Water Migration Setu
29、pThe water migration test setup, shown in Fig. 1, shall consist of a buret, a scale to measure heightsuch as a meter stick yardstick, a support stand, clamps to secure the buret to the support stand, and a flexible hose or tube. Thescale to measure water column height shall be capable of measuring a
30、ccurately to 61mm60.063 in.8. Sampling and Test Specimens8.1 SamplingTest at least five specimens per test condition unless valid results can be gained through the use of fewerspecimens, as in the case of a designed experiment. For statistically significant data, consult the procedures outlined in P
31、racticeE122. Report the method of sampling.8.2 Test Specimens:8.2.1 Core GeometryHoneycomb core material test specimens shall have a square or rectangular cross-section. Therecommended minimum specimen size is 75 mm 3.0 in. in length by 75 mm 3.0 in. in width by 13 mm 0.5 in. thick.NOTE 1The honeyco
32、mb core specimens cross-section is defined to be in the facing plane, in regard to the orientation that the core would be placedin a structural sandwich construction. For a honeycomb core the cross-section is in the plane of the cells, which is perpendicular to the orientation of thecell walls.F1645
33、/F1645M 1228.2.2 Core Preparation and MachiningPrepare the honeycomb core material samples so that the facing plane surfaces areparallel to each other and perpendicular to the sides of the core. Take precautions when cutting specimens from large sheets of corematerial to avoid notches, undercuts, ro
34、ugh or uneven surfaces due to inappropriate machining methods. Obtain final dimensionsby lubricated precision sawing, milling, or grinding. The use of diamond tooling has been found to be extremely effective for manymaterial systems. Record and report the honeycomb core material specimen cutting pre
35、paration method.8.2.3 FacingsThe honeycomb core material shall be bonded to impermeable, transparent facings which permit visualobservation into the honeycomb core cells by illumination. Clear plastic facings are recommended, for ease of locating a hole overa single cell as well as observation of wa
36、ter migration (see Fig. 2).8.2.4 AdhesiveThe honeycomb core material shall be bonded to the facings using a water-resistant adhesive. Use of a clearadhesive is recommended. The adhesive shall be applied so that fairly heavy fillets form between the honeycomb core materialcell walls and the facings,
37、thus assuring a watertight joint between the facings and core. After bonding the facings to the core, thehoneycomb core material specimen shall be inspected for flawed or damaged cells, porous or cracked adhesive, and other defectswhich can become pathways for water seepage or flow from cell to cell
38、, thus invalidating results.8.2.5 Specimen Preparation for Water IntroductionA hole shall be drilled through the upper facing over one centrally locatedhoneycomb core material cell. The hole shall permit access of water into only one cell.Asuitable connection, such as a tube bondedover or into the h
39、ole, shall be provided for the application of hydrostatic pressure (see Fig. 2). If the amount of water transferredis monitored by mass, an appropriate seal shall be used to cover the hole, to prevent water loss during weighings.8.3 LabelingLabel the test specimens so that they will be distinct from
40、 each other and traceable back to the sheet of origin,and will neither influence the test nor be affected by it.9. Calibration9.1 The accuracy of all measuring equipment shall have certified calibrations that are current at the time of use of the equipment.10. Conditioning10.1 The recommended pre-te
41、st condition is effective moisture equilibrium at a specific relative humidity as established by TestFIG. 1 Water Migration Test SetupF1645/F1645M 123Method D5229/D5229M; however, if the test requestor does not explicitly specify a pre-test conditioning environment, noconditioning is required and th
42、e test specimens may be tested as prepared.10.2 The pre-test specimen conditioning process, to include specified environmental exposure levels and resulting moisturecontent, shall be reported with the test data.NOTE 2The term moisture, as used in Test Method D5229/D5229M, includes not only the vapor
43、 of a liquid and its condensate, but the liquid itselfin large quantities, as for immersion.10.3 If no explicit conditioning process is performed the specimen conditioning process shall be reported as “unconditioned”and the moisture content as “unknown”.11. Procedure11.1 Parameters to Be Specified B
44、efore Test:11.1.1 The specimen sampling method, specimen geometry, and conditioning travelers (if required).11.1.2 The properties and data reporting format desired.NOTE 3Determine specific material property, accuracy, and data reporting requirements prior to test for proper selection of apparatus.11
45、.1.3 The environmental conditioning test parameters.11.1.4 The buret measurement accuracy.11.2 General Instructions:11.2.1 Report any deviations from this test method, whether intentional or inadvertent.11.2.2 If honeycomb core material density is to be reported, then obtain these samples from the s
46、ame sheet of honeycomb corematerial being tested. Density may be evaluated in accordance with Test Method C271/C271M.11.2.3 Following final honeycomb core material specimen machining, but before conditioning and testing, measure thespecimen length and width (including the facings) at three places. T
47、he thickness of the specimen (including the facings) shall bemeasured at four locations surrounding the primary honeycomb core cell, and recorded as the average of the four measurements.The accuracy of these measurements shall be within 1.0 % of the dimension. Measure the specimen length and width w
48、ith anaccuracy of 6250 m 60.010 in. Measure the specimen thickness with an accuracy of 625 m 60.001 in. Record thedimensions to three significant figures in units of millimeters inches.11.2.4 If the amount of water transferred into the honeycomb core material specimen is to be measured by mass, dete
49、rmine themass of the specimen (including the facings and seal) with an accuracy of 60.5 %.11.3 Condition the specimens as required. Store the specimens in the conditioned environment until test time, if the testenvironment is different than the conditioning environment.11.4 Following final specimen conditioning, but before testing, re-measure the specimen length, width and thickness as in11.2.3. If the amount of water transferred is to be measured by mass, re-measure the specimen mass (including the facings andseal) as in 11.2.4.
